This invention relates to an operation apparatus for closing/opening, for example, a vacuum circuit breaker having a small capacity, with use of an operation rod.
FIG. 24 shows the conventional operation apparatus of a vacuum circuit breaker. As shown in FIG. 24, a vacuum circuit breaker 93 is held by an upper holder 92 of a switching board 91 which is mounted on a carriage. The vacuum circuit breaker 93 has a mobile contact which is held by an operation rod 94 for operating. The operating rod 94 is provided with an insulating rod 95, and then connected to an operation mechanism provided to the lower portion of the switching board 91.
The operation mechanism comprises an electromagnet 96, a lever 102 provided above the electromagnet 96 and being rotatable with respect to a rotation axis 97, and an iron piece 103 attached to the lever 102 so as to be attracted by the electromagnet 96 when energizing the electromagnet 96. One end of the lever 102 is connected to the insulating rod 95 via a connector 98 and a connecting spring 99, and the other end is connected to a breaker opening spring 100 via a connector 101.
In the operation apparatus constituted as above, when the closing electromagnet 96 is energized, the iron piece 103 is attracted by the electromagnet 96, thereby the lever 102 is rotated in a counter clockwise direction with respect to the rotation axis 97. The rotation force of the lever 102 drives the operation rod 94 upward, thereby the vacuum circuit breaker 93 is closed.
When the closing electromagnet 96 is deenergized, the lever 102 is rotated in a reverse direction by the elastic force of the breaker opening spring 100. The operation rod 94 is thereby driven downward, then the vacuum circuit breaker 93 is opened.
With such a structure of the conventional operation apparatus of a vacuum circuit breaker, however, a large magnetic force needs to be produced to attain the driving force enough to close the vacuum circuit breaker 93. In other words, in order to drive the operation rod 94 to close the breaker 93, the magnet force must be larger than the breaker opening spring 100. The electromagnet 96 thus inevitably needs to be formed large. Further, the electromagnet 96 must be constantly energized when the vacuum circuit breaker 93 is closed. Possibly, the contact pressure between the mobile contact and the fixed contact, is not sufficient.
In order to attain such a large driving force only by the breaker opening spring 100, the electromagnet 96, and the lever 102, the operation mechanism is inevitably so complicated and formed to be large.